Photographic processes and compositions



United States Patent O 3,549,364 PHOTOGRAPHIC PROCESSES AND COMPOSITIONS Meroe M. Morse, Boston, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 438,044, Mar. 8, 1965. This application Dec. 15, 1967, Ser. No. 690,728

Int. Cl. G03c 5/54, 5/30 US. C]. 96-29 11 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation-in-part of application Ser. No. 438,044, filed March 8, 1965, and now abandoned.

BACKGROUND OF THE INVENTION Photographic processes for forming a silver image by diffusion transfer are well known. Processes for forming a usable negative image along with the positive silver transfer image are also known. In such processes a lightsensitive silver halide emulsion which has been exposed to contain a developable image is typically contacted with an aqueous alkaline processing composition including a silver halide solvent and a silver halide developing agent; exposed and developable silver halide is reduced to image silver to form a negative image and at substantially the same time an imagewise distribution of a soluble silver complexe is formed in terms of unexposed areas of the emulsion. This imagewise distribution is transferred at least in part, by imbibition, to a superposed image-receiving layer where it is reduced to image silver to form a pOSitive silver transfer image.

It is frequently desirable in such processes to employ a high-energy silver halide developing agent; use of such high-energy developing agent greatly increases the potential problems of either or both oxidized and unoxidized developing agent being present on the image in amounts suflicient to affect the quality of the image. Unoxidized developing agent may react with atmospheric oxygen to form a colored product which stains the highlights. On the other hand, oxidation products of developing agent may have a tendency to oxidize the image silver, thereby causing the image to fade or lose density.

To obviate the above-mentioned problems, it has heretofore been customary to subject at least the negative image to an after-treatment, e.g., washing, in order to remove such residual developing agent.

The present invention is directed to developing compositions which obviate or greatly reduce the need for aftertreatment.

SUMMARY OF THE INVENTION The present invention is directed to processing compositions for use in silver diffusion transfer processes for forming a usable negative image along with a positive silver transfer image, the compositions including the novel combination of a high energy aminophenol silver halide developing agent containing in one or both of the positions ortho to the phenolic hydroxyl group an amino, alkyl or alkoxy group; and a low energy ascorbic acid or hydroxylamine silver halide developing agent, the low energy developing agent being present in substantially greater concentration than the high energy developing agent, the amount of each of the developing agents alone being insufficient to develop appreciable negative density, but the respective amounts together providing a synergistic effect whereby the combination of developing agents in the processing compositions is capable of providing, upon development, a negative image having a desired usable density. The processing composition further includes at least one silver halide solvent and at least one alkaline material in sufiicient quantity to provide a pH of at least 10.5.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the preferred embodiment, the processing composition containing the aforementioned novel combination of silver halide developing agents further includes as the silver halide solvent or complexing ingredients the combination of cysteine and a nitrogenous base, as described and claimed in applicants US. Pat. No. 3,343,958. The processing composition is further characterized by having a pH of from 10.5 to about 12.5.

As was mentioned previously, the present invention is directed to novel processing compositions for use in diffusion transfer systems for preparing a usable negative silver image along with a positive silver transfer image and to photographic processes employing the same.

A primary object of this invention, therefore, is to provide novel products and processes of the foregoing description.

Another object is to provide novel silver halide developing compositions which obviate or greatly reduce the need for after-treatment to obtain stable silver images.

These and other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description.

Many high-energy silver halide developing agents are known. One class of these known high-energy developers are the aminophenols, e.g., 4-amino-phenols having a lower alkyl, lower alkoxy, and/ or an amino group in a position or the positions ortho to the phenolic hydroxyl group. Particularly useful examples of such high energy silver halide developing agents include 2,4-diamino-ortho-cresol, 4-amino-2,6-dimethyl-phenol and 2,6-dimethoxyl-4-aminophenol. As examples of other high-energy aminophenol developers of the above-mentioned class, mention may be made, for example, of those disclosed in US. Pat. No. 3,108,001 issued to Milton Green.

It has now been found that such a high-energy silver halide developing agent may be employed in extremely low concentrations if it is employed in combination with a high concentration of a low-energy silver halide developing agent. The synergistic effects so obtained greatly expands the usefulness of such high-energy silver halide developing agents. Particularly useful low-energy silver halide developing agents are those which have substantially colorless oxidation products and/or are volatilized from the image, particularly the ascorbic acids, such as ascorbic acid, isoascorbic acid, etc., and hydroxylamines,

such as N,N-diethyl-hydroxylamine, N,N-diethoxyethyl hydroxylamine and N,N-dimethoxyethyl-hydroxylamine. Suitable hydroxylamine silver halide developing agents include those disclosed in U.S. Patents Nos. 2,857,276, is sued to Edwin H. Land et al., and 3,287,125 issued to Milton Green, Adnan A. Sayigh and Henri Ulrich.

Processing compositions containing the novel synergistic combination of developing agents of this invention have been found, according to the present invention, to be particularly useful in photographic systems wherein one desires to obtain a fully developed and fixed negative silver image of good density, contrast and stability along with a positive silver transfer image.

Processing compositions in which the combination of developing agents of this invention are intended to be employed in such processes in general further include a silver halide solvent or fixing agent, e.g., sodium or potassium thiosulfate, etc. and an alkaline material such as sodium hydroxide, diethylamine, sodium carbonate, etc. in an amount suflicient to provide a pH of at least 10.5, preferably from 10.5 to about 12.5 With a pH below about 10.5 the development time is appreciably slower.

While any of the known complexing ingredients may be contained in the processing compositions contemplated by this invention, of particular use is the combination of complexing ingredients disclosed in my U.S. Patent No. 3,343,958. As is disclosed therein, the combination of cysteine and a nitrogenous base, e.eg., diethylamine, has been found to be a very effective complexer or solvent for sliver halide, forming a highly stable silver complex.

The processing compositions may also contain additional reagents performing specific desired functions, e.g., viscosity-increasing, film-forming materials such as sodium carboxymethyl cellulose, hydroxyethyl cellulose, etc.; antifoggants, preservatives, toning agents, etc.

The respective ingredients of the processing composition may be present initially in the aqueous medium therefor, or any or all of them may be present initially in the photographic product, e.g., the photosentitive element or the image-receiving element, in which case the desired composition may be formed by applying thereto the aqueous medium, e.g., during the development step.

The following examples show by way of illustration and not by way of limitation the practice of this invention.

EXAMPLE 1 A photosensitive element having a silver iodobromide emulsion on a film base was exposed and then developed by spreading between the thus exposed emulsion and a superposed surface hydrolyzed cellulose acetate sheet a processing composition comprising the following proportions of ingredients:

Water-9.02 cc.

Hydroxyethyl cellulose0.41 g. Sodium sulfite-0.33 g. Potassium thiosulfate0.14 g. Ascorbic acid0.60 g. 2,4-diamino-ortho-cresol0.02 g. Cysteine-0.02 g. Diethylamine-0.50 g.

Sodium hydroxide-0.25 g.

Aqueous solution of sodium sulfide (156mg. Na S/cc.)-

Aqueous solution of lead acetate and cadmium acetate (100 cc. H O, 2.9 g. lead acetate; 2.1 g. cadmium acetate)0.34 cc.

After an imbibition period of 40 seconds, the spreader sheet was removed to reveal a fully developed and fixed negative on the photosensitive element and a good quality positive silver transfer image in the solidified layer of processing fluid adhered to the hydrolyzed surface of the cellulose acetate sheet.

EXAMPLE 2 A photosensive element having a silver iodobromide emulsion on film base was exposed and processed by spreading a layer of processing fluid, approximately 0.0020 thick, between the exposed negative and a surface hydrolyzed sheet of cellulose acetate. The processing fluid comprised:

Water9.l cc.

Hydroxyethyl cellulose0.4l g.

Sodium hydroxide-$.26 g.

Sodium sulfite0.33 g.

Potassium thiosulfate0.14 g.

Diethylamine-0.5 cc.

Ascorbic acid0.6 g.

2,G-diamino-ortho-cresol-0.02 g.

Aqueous solution of sodium sulfide of sodium sulfide (156 mg. Na S/cc.)0.0l1 cc.

Aqueous solution of lead acetate and cadmium acetate cc. H O, 2.9 g. lead acetate; 2.1 g. cadmium acetate)-0.34 cc.

After an imbibition period of 1 minute, the cellulose ace tate sheet was separated from the exposed negative to provide a negative silver image, and a positive silver transfer image in a solidified layer of processing fluid adhered to the hydrolyzed surface of the cellulose acetate sheet.

EXAMPLE 3 The procedure described in Example 2 was repeated using the following processing composition:

Water9.0 cc.

Sodium carboxymethyl cellulose0.4 g.

Sodium sulfite-- 0.33 g.

Potassium thiosulfate0.l4 g.

2,G-dimethoxy-4-amino-phenol hydrochloride-0.08 g.

Ascorbic acid0.60 g.

Diethylamine0.42 cc.

Sodium hydroxide-0.26 g.

Aqueous solution of sodium sulfide (156 mg. Na S/cc.)-

Aqueous solution of lead acetate and cadmium acetate (100 cc. H O, 2.9 g. lead acetate; 2.1 g. cadmium acetate)0.36 cc.

EXAMPLE 4 The procedures described in the preceding examples were repeated using baryta paper instead of the cellulose acetate sheet. The solidified layer of processing fluid adhered to the baryta paper when it was separated from the developed negative.

In the foregoing illustrative examples the silver precipitating nuclei for initiating and facilitating reduction of silver halide to image silver (lead sulfide and cadmium sulfide) were present initially in the processing fluid. Such procedures are described, forexample, in U.S. Patent No. 2,662,822 issued to Edwin H. Land. The silver precipitating nuclei may alternatively be present in the silverreceptive stratum, e.g., to provide one of the vigorous silver precipitating environments described, for example, in U.S. Pats. Nos. 2,698,237 and 2,698,245 issued to Edwin H. Land.

The following three examples together illustrate the synergistic effect obtained by the novel combination of developing agents of this invention.

EXAMPLE 5 A photosensitive element having a silver iodobromide emulsion on a film base was exposed and then developed by spreading between the thus-exposed emulsion and a superposed surface hydrolyzed cellulose acetate sheet a processing composition comprising the following proportions of ingredients:

Water9.02. cc.

Hydroxyethyl cellulose-0.41 g. Sodium sulfite0.33 g. Potassium thiosulfate0.14 g. Ascorbic acid-0. 60 g. 2,4diamino-orthocresol0.02 g. Cysteine-0.02 g. Diethylamine-0.50 cc.

Sodium hydroxide-0.25 g.

After an imbibition period of about 40 seconds the cellulose acetate sheet was removed to reveal afully developed and fixed negative having a D of 1.5 and a D of 0.2.

EXAMPLE 6 Example 5 was repeated eliminating the ascorbic acid from the developing composition. An extremely faint (D 0.15 above base density) image was obtained.

EXAMPLE 7 Example 5 was repeated eliminating the 2,4diaminoorthocresol from the developing composition. The resulting image was even fainter or had an even lower density (D 0.05 above base density) than the negative prepared in Example 6.

From Examples 6 and 7 it will be observed that the density obtained from the combination of ascorbic acid and 2,4-diamino-orthocresol is appreciably greater than the sum total of the densities obtained from the same concentrations of individual components.

In other words, there is a synergistic reaction between the two developing agents, neither of which alone was capable, in the concentrations used, of providing a visible image of usable density, but the two developing agents together did in fact provide an image of excellent negative density and contrast.

The following example represents developing time series analyses illustrating the effect of pH upon development time.

EXAMPLE 8 A light-sensitive silver iodobromide emulsion was exposed and then developed with a first processing composition having a pH above 11.0 and comprising the following proportions of ingredients:

Water-27 0.7 cc.

Ascorbic acid1'8.0 g. 2,4-diamino-orthocresol0.6 g. Sodium hydroxide7.5 g. Sodium sulfite9.9 g. Diethylamine15.0 cc.

After various periods of contact time with the developer, followed by the standard procedures of rinsing in distilled water, placing in a standard stop bath, then a standard fixing solution, rinsing in cold running water and finally drying; development was determined. A second set of development times were run by exposing and developing a similar light-sensitive emulsion with a second processing composition in which the amounts of sodium hydroxide and diethylamine were adjusted so that the processing composition had a pH of 8.5 to 9.0.

The respective D s obtained at the indicated time intervals are set forth in the following table:

TABLE Com os'tonl see 1. 98 Composition 2, see 28 with composition 2 (pH 8.5-9.0), the D obtained after two minutes was 1.27.

EXAMPLE 9 COMPOSITION 3 Sec.

The results showed that composition 3 afforded lower D s and required longer development times than did composition 1.

EXAMPLE 10 The negative image prepared in Example 5 was subjected to accelerated tests for stability to light, heat and humidity (ultraviolet lamp for 72 hours; relative humidity at F. for 40 hours; 80% relative humidity at F. for 16 hours in the presence of powdered sulfur), and was found to be exceptionally stable although perhaps not of archival stability. A fully developed and fixed negative prepared as described in Example 1 has been found to be stable, e.g., no density fading and density increase in highlights, when stored at room temperature and humidity for over two years.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A photographic process comprising the steps of contacting an exposed light-sensitive silver halide emulsion containing a developable image with an aqueous alkaline processing composition having a pH above 10.5 and including a silver halide solvent, a high energy aminophenol silver halide developing agent containing in a position ortho to the phenolic hydroxyl group at least one substituent selected from the group consisting of amino, lower alkyl and lower alkoxy groups and a low-energy silver halide developing agent selected from the group consisting of ascorbic acids and hydroxylamines, said low-energy developing agent being present in substantially greater concentration than said high-energy developing agent, the amount of each of said low-energy and high-energy developing agents alone being insuflicient to develop appreciable negative density, but said respective amounts together providing a synergistic effect whereby said combined developing agents are capable of developing exposed silver halide to a desired usable density;

reducing exposed and developable silver halide to image silver to form a fully developed and fixed negative silver image while at substantially the same time forming an imagewise distribution of a soluble silver complex in terms of unexposed areas of said emulsion;

and transferring said imagewise distribution, at least in part, by imbibition, to a superposed stratum where it is reduced to impact thereto a positive silver transfer image.

2. A process as defined in claim 1 wherein the pH of said composition is between 10.5 and about 12.5.

3. A process as defined in claim 1 wherein said highenergy silver halide developing agent is 2,4 diaminoortho-cresol and said low-energy silver halide developing agent is ascorbic acid.

4. A process as defined in claim 1 wherein said highenergy silver halide developing agent is 2,4-diamino-o1thocresol and said low-energy silver halide developing agent is isoascorbic acid.

5. A process as defined in claim 1 wherein said highenergy silver halide developing agent is 2,4-diamino-ortho cresol and said low-energy silver halide developing agent is N,N-diethyl-hydroxylamine.

6. A process as defined in claim 1 wherein said highenergy silver halide developing agent is 4-amino-2,6-dimethyl-phenol and said low-energy silver halide developing agent is isoascorbic acid.

7. A process as defined in claim 1 wherein said highenergy silver halide developing agent is 2,6-dimethoxy-4- aminophenol and said low-energy silver halide developing agent is isoascorbic acid.

8. A process as defined in claim 1 wherein a fully developed and fixed negative image is formed as a function of said development in addition to said silver transfer image.

9. A photographic processing composition for use in processes for forming silver transfer images comprising an aqueous alkaline solution containing a silver halide solvent, a high-energy aminophenol silver halide developing agent containing in a position ortho to the phenolic hydroxyl group at least one substituent selected from the group consisting of amino, lower alkyl and lower alkoxy groups and a low-energy silver halide developing agent selected from the group consisting of ascorbic acids and hydroxyl amines, said low-energy developing agent being present in substantially greater concentration than said high-energy developing agent, the amount of each of said low-energy and high-energy silver halide developing agent alone being insufiicient to develop appreciable negative density, but said respective amounts together providing a synergistic effect whereby said combined developing agents are capable of developing exposed silver halide to a desired usable density, said processing composition having a pH above 10.5.

10. A composition as defined in claim 9 wherein the pH of said composition is between 10.5 and about 12.5.

11. A composition as defined in claim 9 wherein said high-energy silver halide developing agent is 2,4-diaminoortho-cresol.

References Cited UNITED STATES PATENTS 2,060,596 11/1936 Schneider et al, 9666.4 2,857,276 10/1958 Land et a1 9629 3,022,168 2/ 1968 Stjiirnkvist 9666HD 3,041,170 6/1962 Haist et al. 9666HD 3,134,673 5/1964 Gauguin et al. 9666 OTHER REFERENCES Glafkides, P., Photographic Chemistry, London, Fountain Press, 1958, vol. 1, pp. .118, 119, 122, 125, 126.

WILLIAM D. MARTIN, Primary Examiner M. SOFOCLEOUS, Assistant Examiner US. 01. X.R. 

